Emergency vehicles require warning lights arranged about the exterior to emit warning light signals in patterns specified by various federal and state regulations as well as standards set by industry organizations. Standards relevant to this disclosure include: the Federal KKK Standard for ambulance lighting, the Society of Automotive Engineers (SAE) Surface Vehicle Recommended Practice standards including SAEJ595, J1849, J759, J845, National Fire Protection Association (NFPA) standard 1901, and California Code of Regulations Title 13. The standards set forth in these documents include specifications for exterior warning lighting for emergency vehicles. To meet these requirements, it is frequently necessary to mount warning lights to the exterior surface of motor vehicles. Motor vehicle bodies are typically constructed of sheet material such as sheet steel, aluminum and/or plastic. Typically, a vehicle to which warning lights are to be mounted has already been constructed, so access to the rear side of the sheet material forming the exterior of the motor vehicle is obstructed. The situation where access to the rear of a mounting surface is obstructed is typically referred to a “blind” installation.
One approach to a blind installation has been to use individual screw grommets placed in holes formed in the vehicle's sheet material. Screw grommets are typically configured for use in either a round hole or a shaped hole. Shaped holes are typically in the form of a square where the outside surfaces of the head of the screw grommet match the shape of the hole and prevent rotation of the screw grommet in the hole. Round screw grommets employ retaining mechanisms configured to be inserted through a round hole. Screw grommets used in round holes can be problematic in that the engagement between the outside surface of the screw grommet and the round hole is relatively light, meaning that relatively little rotational force applied to the screw grommet can cause rotation of the screw grommet relative to the work piece and prevent proper insertion of a fastener through the screw grommet. A common problem with individual screw grommets is that the screw grommet will rotate behind the warning light, preventing advancement of fasteners through the screw grommet to secure the light to the vehicle. Once a screw grommet begins rotating behind a partially installed warning light, removal of the fastener and warning light is problematic.
Alternatively, sheet metal screws have been employed directly though the sheet material of the vehicle exterior. Sheet metal fasteners have a tendency to strip, preventing secure attachment of the warning light to the vehicle. Further, sheet metal fasteners have the potential to exert excessive force on the warning light, resulting in bent or cracked warning light housings.
There is a need for a simplified apparatus and method for securing warning lights to the exterior of motor vehicles.